Soil Compaction

Posted by Randy - May 28th, 2011

Root Stressed Fir

Root Stressed Firs

Here is a remnant group of large Douglas Firs, all showing classic signs of advanced root stress: thin and straggly canopies, weak epicormic growth, and deadwood accumulation. The root stress could be caused by many factors- root disease or rot, poor drainage, herbicides, or a combination of multiple factors. In this case, the root stress is most likely caused by soil compaction. These trees are located, ironically, in a tree nursery, and have been subjected to years of pressure on their root zones from truck traffic and tree storage. Soil compaction often causes direct injury to shallow roots, but also damages the soil’s structure, reducing the soil’s ability to hold air and moisture. A tree’s critical root zone should be protected with edged borders or fencing, and cooled with a generous layer of organic mulch. Root-stressed trees can benefit from aeration, vertical mulching, inoculation with fertilizer and/or mycorrhizae, or even topsoil replacement, but in any case, these particular trees would likely have poor prospects for recovery- they may be too far gone.

Prevention is the best medicine for soil compaction. For optimal tree health, safety, and longevity, give your trees enough undisturbed ground space to thrive, and protect their vulnerable roots as early in the development process as possible.

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